As shown by a picture posted onto a Facebook page, the magazine of a real dumdum bullet was found in Wong Tai Sin, a protest area, around 23: 00 on August 24, and it is believed to have been left behind by the Hong Kong Police. Expanding bullets, also known colloquially as dumdum bullets, are projectiles designed to expand on impact. They were used in Tiananmen Square Massacre and are generally prohibited for use in war. President Donald Trump and many US Senators and House Representatives have explicitly warned China against remaking Tiananmen Square Massacre in Hong Kong or else there will be swift and serious consequences.